The quantum mechanical effect (QME) in nanoscale MOSFETs has become more and more important. The quantization of the space charge density in bulk-MOS compact models is usually modeled by the van Dort model with a simple modification of intrinsic carrier density. However, for double-gate MOSFET compact modeling, there is no simple solution even without considering the QME. In this work, the QM correction in explicit surface potential for bulk-MOS is extended to common-gate asymmetric double-gate MOSFET modeling. The transition from partially depleted to fully-depleted operation is seamlessly built into the model without any fitting parameters. The surface potential can be applied to the drain current model as it contains the essential physics that scales with the DG MOSFET structures.